Homework Help:
Momentum and Impulse

18. A 75 kg swimmer dives horizontally off a 300 kg raft. If the speed of the raft immediately after the swimmer dives off is 1.0 m/s, at what speed did the diver leave the raft?

A. 2 m/s B. 4 m/s C. 6 m/s D. 8 m/s E. 10 m/s

2. Relevant equations

p=mv

3. The attempt at a solution
I can't figure out how to use the equation to solve the problem. The only answer that I could find was 4 m/s and I did that by taking 300/75. Can somebody work it out step-by-step for me please?